Abstract

The Neutral-Point Clamped (NPC) three-level inverter is a promising multilevel topology in the application of Electric Vehicle (EV). However, the growing requirements by the EV initiate the thermal unbalance problem for this inverter topology. The present thesis highlights the performance of the NPC three-level inverter supplying a Permanent Magnet Synchronous Motor (PMSM) in the application of EV. The PMSM is considered to operate in the region below the base speed. In this condition, there is an unbalance of conduction power loss among the semiconductors of the inverter. The project deals with the conduction power losses of the semiconductors in a NPC three-level inverter controlled with special Space Vector Modulation (SVM) methods. In order to find an appropriate method for balancing the conduction power loss of devices, three SVM methods, “Normal”, “O2” and “O3” are compared. By implementing these three techniques, primarily, the “conduction duty cycle” of the devices is calculated to demonstrate the duration of conducting for each device. Afterwards, the conduction power loss of devices is computed in MATLAB/Simulink. In addition, the impact of two parameters, modulation index and power factor, on conduction duty cycle and conduction power loss is investigated. Furthermore, Comparison of the total harmonic distortion of the line-to-line current for different modulation indices is presented for all three modulation techniques. According to the detailed comparisons of methods, O2 Space Vector Modulation technique stands out as a better candidate for thermal redistribution among semiconductors.